Method and apparatus for optical phase error correction

Abstract

The phase value of a phase-sensitive optical device, which includes an optical transport region, is modified by laser processing. At least a portion of the optical transport region is exposed to a laser beam such that the phase value is changed from a first phase value to a second phase value, where the second phase value is different from the first phase value. The portion of the optical transport region that is exposed to the laser beam can be a surface of the optical transport region or a portion of the volume of the optical transport region. In an embodiment of the invention, the phase value of the optical device is corrected by laser processing. At least a portion of the optical transport region is exposed to a laser beam until the phase value of the optical device is within a specified tolerance of a target phase value.

The invention claimed is: 
     
       1. A method for modifying a phase value of a phase-sensitive optical device comprising an optical transport region, the method comprising the step of:
 exposing at least a portion of the optical transport region to a laser beam such that the phase value changes from a first phase value to a second phase value, wherein the second phase value is different from the first phase value. 
 
     
     
       2. The method of  claim 1 , wherein exposing at least a portion of the optical transport region to a laser beam does not induce oxidation of the at least a portion of the optical transport region. 
     
     
       3. The method of  claim 1 , wherein:
 the laser beam has a specified intensity; 
 exposing at least a portion of the optical transport region to a laser beam comprises exposing the at least a portion of the optical transport region to the laser beam for a specified exposure time; and 
 the specified intensity and the specified exposure time are based at least in part on a difference between the first phase value and a target phase value. 
 
     
     
       4. The method of  claim 3 , further comprising the step of:
 measuring the first phase value prior to exposing at least a portion of the optical transport region to a laser beam. 
 
     
     
       5. The method of  claim 3 , wherein the phase-sensitive optical device is one of a plurality of phase-sensitive optical devices, further comprising the steps of:
 measuring a phase value of at least one phase-sensitive optical device in the plurality of phase-sensitive optical devices prior to exposing at least a portion of the optical transport region to a laser beam; and 
 estimating the first phase value based at least in part on the at least one measured phase value. 
 
     
     
       6. The method of  claim 1 , further comprising the step of:
 upon determining that the second phase value is not within a specified tolerance of a target phase value:
 exposing the at least a portion of the optical transport region to the laser beam such that the phase value changes from the second phase value to a third phase value, wherein the third phase value is different from the second phase value. 
 
 
     
     
       7. The method of  claim 1 , wherein the at least a portion of the optical transport region comprises a surface of the optical transport region. 
     
     
       8. The method of  claim 1 , wherein the at least a portion of the optical transport region comprises at least a portion of a volume of the optical transport region. 
     
     
       9. The method of  claim 1 , wherein:
 the phase-sensitive optical device comprises an end face; 
 the at least a portion of the optical transport region comprises a surface of the optical transport region; 
 the surface of the optical transport region is disposed on the end face; and 
 exposing at least a portion of the optical transport region comprises transmitting the laser beam onto the surface of the optical transport region. 
 
     
     
       10. The method of  claim 1 , wherein:
 the phase-sensitive optical device further comprises a cladding region surrounding the optical transport region; 
 the at least a portion of the optical transport region comprises at least a portion of a volume of the optical transport region; and 
 exposing at least a portion of the optical transport region to a laser beam comprises transmitting the laser beam through at least a portion of the cladding region and into the at least a portion of the volume of the optical transport region. 
 
     
     
       11. The method of  claim 1 , wherein the laser beam has a wavelength from about 300 nanometers to about 2000 nanometers. 
     
     
       12. The method of  claim 1 , wherein the laser beam has a peak pulse intensity of about 12 megawatts/square centimeter. 
     
     
       13. The method of  claim 12 , wherein exposing at least a portion of the optical transport region to a laser beam comprises exposing the at least a portion of the optical transport region to the laser beam for an exposure time of about 10 nanoseconds. 
     
     
       14. The method of  claim 1 , wherein the phase-sensitive optical device is selected from the group consisting of:
 an optical-fiber based device; 
 a microbead resonator; 
 an optical waveguide device; 
 an electro-optic polymer device; 
 a free carrier effect based modulator; and 
 an electro-optic device. 
 
     
     
       15. The method of  claim 1 , wherein the phase-sensitive optical device is fabricated from at least one material selected from the group consisting of:
 silica; 
 silicon; 
 germanium; 
 lithium niobate; 
 a compound semiconductor; 
 a polymer; and 
 a non-centro-symmetric crystalline material. 
 
     
     
       16. An apparatus for correcting a phase value of a phase-sensitive optical device, the apparatus comprising:
 a laser configured to transmit a laser beam; 
 an optical system configured to:
 in a first operational mode, receive the laser beam from the laser and focus the laser beam onto at least a portion of an optical transport region of the phase-sensitive optical device, wherein, when the at least a portion of the optical transport region of the phase-sensitive optical device is exposed to the laser beam, the phase value of the phase-sensitive optical device is modified; and 
 in a second operational mode, generate an image of at least a portion of the phase-sensitive optical device; 
 
 an alignment system configured to change a position of the laser beam with respect to a position of the phase-sensitive optical device; 
 a phase measurement system configured to measure the phase value of the phase-sensitive optical device; and 
 at least one optical fiber probe configured to operably couple the phase-sensitive optical device to the phase measurement system. 
 
     
     
       17. The apparatus of  claim 16 , wherein the alignment system comprises at least one alignment system selected from the group consisting of:
 a stage configured to:
 hold the optical device; and 
 move the optical device; 
 
 a carriage configured to move the optical system; and 
 a deflection system configured to move the position of the laser beam. 
 
     
     
       18. The apparatus of  claim 16 , wherein the laser beam has a wavelength from about 300 nanometers to about 2000 nanometers. 
     
     
       19. The apparatus of  claim 16 , further comprising a system controller configured to control operation of the laser, the optical system, the alignment system, the phase measurement system, and the at least one optical fiber probe. 
     
     
       20. The apparatus of  claim 19 , wherein the system controller comprises:
 a processor; 
 memory operably coupled to the processor; and 
 a data storage device operably coupled to the processor, wherein the data storage device stores computer program instructions, which, when executed by the processor, cause the processor to execute a method comprising the steps of:
 measuring a first phase value of the phase-sensitive optical device; 
 comparing the measured first phase value with a target phase value; 
 determining whether the measured first phase value is within a specified tolerance of the target phase value; and 
 upon determining that the measured first phase value is not within the specified tolerance of the target phase value, performing the steps of:
 (a) exposing at least a portion of an optical transport region of the phase-sensitive optical device to a laser beam such that the phase value of the phase-sensitive optical device is modified; 
 (b) measuring the phase value of the phase-sensitive optical device after exposing the at least a portion of the optical transport region to the laser beam; 
 (c) comparing the measured phase value with the target phase value; 
 (d) determining whether the measured phase value is within the specified tolerance of the target phase value; and 
 (e) upon determining that the measured phase value is not within the specified tolerance of the target phase value, repeating steps (a)-(d).